Wild Fulvous Fruit Bats (Rousettus leschenaulti) Exhibit Human-Like Menstrual Cycle1

Abstract

We investigated the menstrual cycle of wild fulvous fruit bats (Rousettus leschenaulti), focusing on changes in the endometrial and ovarian structure and pituitary and steroid hormones. The menstrual cycle lasts for 33 days in bats studied in their natural habitat and in captivity. Vaginal bleeding was restricted to a single day (Day 1). A preovulatory follicle was found in the ovary on Day 18 when the levels of LH and FSH reached their maxima, accompanied by a thickened endometrium. On Day 24, serum levels of progesterone and estradiol-17 were also maximal, and uterine glands increased in size. After that, the levels of progesterone dropped precipitously, leading to menstrual bleeding. Both the morphologic and hormonal changes observed in fulvous fruit bats during the menstrual cycle resemble similar changes in humans. Fulvous fruit bats may be useful nonprimate laboratory models to study menstruation and menstrual dysfunction.

The Brain-Uterus Connection: Brain Derived Neurotrophic Factor (BDNF) and Its Receptor (Ntrk2) Are Conserved in the Mammalian Uterus

“…Here, using complementary molecular techniques, we demonstrated the conservation of the coding region of BDNF and Ntrk2 across several mammalian species, the mRNA expression of both genes within the uterus, and the uterine localization of both proteins in two species that menstruate (humans and bats [34]), and four that do not (mice, rats, pigs, and horses). Additionally, we have shown that several protein isoforms of each gene were present in the human uterus, and that the antibodies employed in this study were specific to BDNF and Ntrk2 respectively.…”

“…Collection of the uterine horns of fulvous fruit bats was detailed previously [34]. In brief, the bats were trapped alive on Day 21 (n = 6; the day when menstrual bleeding was observed was designated as Day 1).…”

Ovulation, Fertilization, and Early Embryonic Development in the Menstruating Fruit Bat, Carollia perspicillata

“…Indeed, a number of females with old CLs and menstrual uteri had been housed with males for as little as 5–7 days. This and previous studies of captive‐maintained Carollia sp., sexually isolated Glossophaga soricina , and unmated Molossus rufus (Rasweiler, 1979, 1988, 1991; Rasweiler and de Bonilla, 1992; Rasweiler and Badwaik, 2000) do not support the recent assertion that menstruation in microchiropteran bats is “coitus‐dependent” (Zhang et al, 2007). In this study, in fact, four newly mated females had proliferative (rather than menstrual) uteri.…”

“…Menstruation has also been reported to occur in bats belonging to three other families— Molossus rufus (family Molossidae) (Rasweiler, 1991, 1992), Rousettus leschenaulti (family Pteropodidae) (Zhang et al, 2007), and Myotis ricketti (family Vespertilionidae) (Wang et al, 2008).…”

The Chiropteran Brain Database: Volumetric Survey of the Hypophysis in 165 Species

“…Elsewhere, it has been proposed that megachiropteran bats differ in reproductive physiology as compared to microchiropterans. Zhang et al () measured the serum hormone levels [follicle stimulating hormone, luteinizing hormone, Estradiol‐17 (E 2 ), and Progesterone (P 4 )] and histologically examined the uterine walls every three days following observed menstrual bleeding. The authors found the cyclic hormonal fluctuations and changes in endometrial histology that have parallels to the same variables in human menstrual cycles.…”